In optimization, the negative gradient of a function denotes the direction of steepest descent. Furthermore, traveling in any direction orthogonal to the gradient maintains the value of the function. In this work, we show that these orthogonal directions that are ignored by gradient descent can be critical in equilibrium problems. Equilibrium problems have drawn heightened attention in machine learning due to the emergence of the Generative Adversarial Network (GAN). We use the framework of Variational Inequalities to analyze popular training algorithms for a fundamental GAN variant: the Wasserstein Linear-Quadratic GAN. We show that the steepest descent direction causes divergence from the equilibrium, and guaranteed convergence to the equilibrium is achieved through following a particular orthogonal direction. We call this successful technique Crossing-the-Curl, named for its mathematical derivation as well as its intuition: identify the game's axis of rotation and move "across" space in the direction towards smaller "curling".

通过对变分不等式框架的分析，我们发现在 GAN 的基本变体 Wasserstein Linear-Quadratic GAN 中，直接梯度下降方向会导致不收敛，而特定的正交方向可以实现收敛，我们称之为“通过卷曲”，这是命名来源于其数学推导及感性：识别游戏的旋转轴并向“卷曲”更小的方向移动空间。

使用变分不等式实现GANs的全局收敛到平衡点